source: mainline/kernel/arch/ia32/src/userspace.c@ 1433ecda

/*
 * Copyright (c) 2005 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup ia32
 * @{
 */
/** @file
 */

#include <userspace.h>
#include <arch/pm.h>
#include <stdint.h>
#include <arch.h>
#include <abi/proc/uarg.h>
#include <mm/as.h>
#include <arch/cpu.h>
#include <arch/asm.h>

/** Enter userspace
 *
 * Change CPU protection level to 3, enter userspace.
 *
 */
void userspace(uspace_arg_t *kernel_uarg)
{
        uint32_t eflags = read_eflags();

        asm volatile (
                /* Set up GS register (virtual register segment) */
                "movl %[vreg_des], %%gs\n"

                "pushl %[udata_des]\n"
                "pushl %[stack_top]\n"
                "pushl %[eflags]\n"
                "pushl %[utext_des]\n"
                "pushl %[entry]\n"
                "movl %[uarg], %%eax\n"

                /* %edi is defined to hold pcb_ptr - set it to 0 */
                "xorl %%edi, %%edi\n"

                "iret\n"
                :
                : [eflags_mask] "i" (~EFLAGS_NT),
                  [udata_des] "i" (GDT_SELECTOR(UDATA_DES) | PL_USER),
                  [stack_top] "r" ((uint8_t *) kernel_uarg->uspace_stack +
                      kernel_uarg->uspace_stack_size),
                  [eflags] "r" ((eflags & ~(EFLAGS_NT)) | EFLAGS_IF),
                  [utext_des] "i" (GDT_SELECTOR(UTEXT_DES) | PL_USER),
                  [entry] "r" (kernel_uarg->uspace_entry),
                  [uarg] "r" (kernel_uarg->uspace_uarg),
                  [vreg_des] "r" (GDT_SELECTOR(VREG_DES))
                : "eax");

        /* Unreachable */
        while (1);
}

/** @}
 */